I was in Bruxelles for FOSDEM 2013. As with previous FOSDEM there were too many
interesting talks and people to see. Here is a summary of what I saw:

In the Mozilla's room:

The html5 pdf viewer pdfjs is impressive. The PDF specification is really
scary but this full featured "native" viewer is able to renders most of it
with very good performance. Have a look at the pdfjs demo!

Introduction to webl10n: an internationalization format and library used in
Firefox OS. A successful mix that results in a format that is idiot-proof
enough for a duck to use, that relies on Unicode specifications to handle
complex pluralization rules and that allows cascading translation
definitions.

Status of html5 video and audio support in Firefox. The topic looks like a
real headache but the team seems to be doing really well. Special mention
for the reverse demo effect: The speaker expected some format to be still
unsupported but someone else apparently implemented them over night.

Last but not least I gave a talk about the changeset evolution concept that
I'm putting in Mercurial. Thanks goes to Feth for asking me his
not-scripted-at-all-questions during this talk. (slides)

Victor Stinner has started an interesting project to improve CPython
performance. The first one: astoptimizer breaks some of the language
semantics to apply optimisation on compiling to byte code (lookup caching,
constant folding,…). The other, registervm is a full redefinition of how the interpreter
handles reference in byte code.

After the FOSDEM, I crossed the channel to attend a Mercurial sprint in London.
Expect more on this topic soon.